Delta-Sigma ADC Control Using Signal-Interval OSR Switching
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Solution Overview
Problem
Existing delta-sigma AD converters with fixed oversampling ratios require additional control terminals for OSR adjustments, increasing complexity and terminal count, whereas those with variable OSR often lack efficient control mechanisms.
Innovation Solution
A delta-sigma AD converter with a control terminal for external control signals to set and adjust the oversampling ratio dynamically, allowing for sequential output based on interval information and clock pulses, enabling OSR changes without additional terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dedicated control terminal is added for OSR selection, then the converter can achieve variable oversampling ratio, but the number of terminals increases
Solution Approach 1:
The existing control terminal is made multi-functional by enabling it to serve both as an output control terminal and an OSR setting terminal. The control terminal receives control signals that can designate either output timing or OSR values, allowing a single terminal to perform multiple functions without requiring additional dedicated terminals for OSR selection.
Solution Approach 2:
The invention changes the parameter representation method by encoding OSR settings as time interval information within the control signal itself. Instead of using separate terminals for different settings, the control signal's temporal characteristics (interval between pulses) carry the OSR value, allowing parameter changes without adding hardware terminals.
2Reliability
If the OSR is increased to improve S/N ratio, then the output rate decreases, but if the OSR is decreased to increase output rate, then the S/N ratio deteriorates
Solution Approach 1:
The invention implements dynamic OSR adjustment capability, allowing the oversampling ratio to be changed during operation based on external control signals. This enables the system to adaptively optimize the balance between S/N ratio and output rate by selecting different OSR values according to real-time requirements, rather than being fixed at a single value.
Solution Approach 2:
The control terminal receives periodic control signals with varying time intervals, where each interval corresponds to a specific OSR setting. This periodic control mechanism allows the system to switch between different oversampling ratios at regular intervals or in response to external timing requirements, enabling flexible trade-off management between quality and speed.
Data Source
AI summary
Provided is a delta-sigma AD converter including a delta-sigma modulating section that outputs a digital signal obtained by performing delta-sigma modulation with an oversampling ratio on an input analog signal; a digital filtering section that filters the digital signal with the oversampling ratio; a control terminal into which an external control signal is input; an output control section that performs control to output an output signal based on the filtered digital signal, according to the external control signal; and a setting section that sets the oversampling ratio based on interval information of the external control signal.